There were many philosophies, and the world in general was very religious (although polytheistic). The church was in the midst of all these, and yet was not to be a part of them. With philosophy you had a following in thought, but no necessary application to body. With idolatry you had a physical worship of deity, but no necessary allegiance to one particular god. The church, as the body of Christ, demanded a purity that was very distinct from the society in which it arose. This attribute of the first century church is an identifying factor in recognizing the church today.

Comprised of an Holy People...

The church was to be comprised of people who were pure. They had been washed in the blood of Jesus (I Pt 1:18f; II Cor 6:11, 19f). They were also to remain free of the world's pollutants (I Pt 2:9-12; II Cor 6:14-18). The purity of the church may be summed up by Paul's illustration of the church as the bride of Jesus Christ:

"Husbands, love your wives, just as Christ also loved the church and gave Himself for her, that He might sanctify and cleanse her with the washing of water by the word, that He might present her to Himself a glorious church, not having spot or wrinkle or any such thing, but that she should be holy and without blemish." (Eph 5:25-27).

Comprising the Body of Christ...

The church is the body of Christ (Eph 1:22f; Col 1:18). Christians are members of that body (I Cor 12:27; Rom 12:5). Now, who could seriously conceive of the body of Christ being in any way impure?!

Rebuking the Impure and Unholy...

Consider this simple syllogism:

Primary: The evangelist is God's workman in the church to edify (Eph 4:11f).
Secondary: The evangelist is to reprove and rebuke (II Tim 4:1f).
Conclusion: Therefore, the church is to be engaged in rebuke of that which is unlawful.

Many people do not like for anything negative to be involved in the church. They want all to be positive. But, will anyone in error come out of error, if error is never rebuked? You can't "love" someone out of error. If anything, it will set them even more deeply in it.

Would the man who had his father's wife have repented without the needed rebuke? (I Cor 5:4ff) If Paul's epistles (which contained rebukes) were read in the churches (Col 4:16), do you suppose the negative content was edited out first? The purity of the church demands a public rebuke of wickedness and error. You do not find this in some churches claiming to be Jesus' church!

Conditional Fellowship...

The necessary purity of the church is seen in the conditional fellowship of churches with Christ. In the book of Revelation, John saw Jesus walking among lampstands, which represented fellowship with the churches (Rev 1:12-20). We also see the possibility of a loss of fellowship with Jesus in the removal of their lampstand (Rev 2:5). In addition, we find a conditional fellowship of individuals within the church. Members are to have no fellowship with the unfruitful works of darkness (Eph 5:8-14). They also are not to keep company with a so-called brother participating in the evil of this world (I Cor 5:9-11). They are to withdraw from brethren who walk disorderly (II Th 3:6, 14f).

Conclusion...

The purity of the Lord's church is an important aspect of her identity. If you find a church that will not rebuke error, but instead allow it to remain among them, you have not found the Lord's church. The Lord's church condemns sin and will in no way condone it, no matter how impure the world becomes.